The present invention relates to a vehicle control system of selecting an optimal mode from a plurality of running modes and switching a current mode to an optimal mode, and more particularly to a control system of a hybrid vehicle, which system is arranged to select an optimal mode from a three-dimensional mode map.
Japanese Published Patent Application No. 2003-34153 discloses a hybrid vehicle equipped with a power train system which is arranged such that a brake is attached to one of rotating elements except for a rotating element connected to a driveline output of a two-degree-of-freedom planetary gearset mechanism. This hybrid vehicle is arranged to be capable of selecting a mode from an EV mode of producing a continuously variable transmission ratio only by two motors, an EV-LB mode of driving the two motors under a fixed transmission ratio produced by engaging a brake, an EIVT mode of producing a continuously variable transmission ratio by driving an internal combustion engine and the two motors and by engaging an engine clutch, and an LB mode of producing a fixed transmission ratio by driving the engine and the two motors and by engaging the engine clutch and the brake, which modes have been stored in a mode map, according to a vehicle running condition.